Skip to main content

Full text of "Text Book Of Mechanical Engineering"

See other formats


.

Appendix VI.

1075

again till to a very low value at 1200°. This information is of
the greatest possible value to the designer of boiler furnaces.
Two examples have been given in the diagram, one shewing steel
of high carbon composition, and the other of a milder quality,
and the different results indicate clearly the effect of the presence
of the carbon.

Pp. jpj and 840. Chrome-Vanadium Steel,—Under
this title a new material has been introduced by Captain Sankey
and Mr. Kent Smith. It consists of a carbon steel to which has
been added small percentages of chromium and vanadium, and
the result may be briefly stated as follows:—

Percentages added.

Chromium i%    .
Vanadium   "15%

Chromium i%
Vanadium

:%    - II

•25% J!

Yield Point, tonssq. in.;
	Ultimate   Elongation Stress        on 2 ins. tonssq. in. j   per cent.
	Reduction of Area per cent.


	I
	


	
	j

36-2     :
	48-6   ;    24
	c6*6

49*4
	i 60*4         18*5
	46-3

Crucible                  ( I

Carbon Steel ... J !

16*0

27-0

I     60'o

The last line shews figures for the carbon steel without ad-
mixture, and the other lines indicate the effect of mixing per-
centages of chromium and vanadium to the steel. Higher
strengths, even to 77 tons ultimate, were obtained, but the
elongation then decreased to 13%.

P. 407. Riveted Joints.—A lap joint is essentially an
unsatisfactory construction, and its real strength is a matter of
some doubt. From an experiment made by Prof. Barr and
mentioned in the Inst of Mech. Engineers' Proceedings^ Sept.
1901, Plate 164, it would appear that the actual strength of such
a joint is only about 80% of the value as calculated on p. 407,
For butt joints the usual method of calculation may be fully
accepted.

Example 72.—-Design a single-riveted lap joint for \ in. plates,
-where the rivets and plate are of equally strong material, and the